(Adapted from the applicant's abstract) Obstructive sleep apnea (OSA) is a common disorder with important consequences for afflicted individuals. This disorder is characterized by recurrent pharyngeal collapse during sleep with subsequent repetitive arousals, along with substantial hypoxia and hypercapnia. Associated consequences include daytime somnolence, decreased performance on cognitive and vigilance testing and decreased quality of life. In addition, there is also increasing evidence that OSA may lead to adverse cardiovascular outcomes such as hypertension, arrhythmias, myocardial infarction and stroke. The pathophysiology of sleep apnea is dependent upon a complex interaction between upper airway anatomy, pharyngeal dilator muscle function and ventilatory control mechanisms, and the effects of state related changes in these variables. Substantial literature indicates that this disorder is much more common in men than in women, and that androgens in both men and women can exacerbate the disorder. However, neither the true extent of the effect of androgens on sleep apnea incidence and severity, nor the mechanisms by which androgens predispose to apnea have been well delineated to this point. With the proposed Mentored Patient-Oriented Research Career Development Award, the applicant will build upon his prior experiences investigating the role of androgens in the pathophysiology of sleep apnea. Based upon very positive experiences in the laboratory to date, the applicant is firmly committed to a career in academic pulmonary and critical care medicine, focused primarily on clinical research. The laboratory of Dr. David P. White at the Brigham and Women's Hospital will provide a rich intellectual environment.